Vibrator type electrical circuit interrupter

ABSTRACT

A vibrator type electrical circuit interrupter having normally closed breaker contacts which establish an energizing circuit for an associated electrical coil and which are operated to an electrical circuit open condition upon the energization of the coil to interrupt the energizing circuit. A bimetallic element of the type which deflects in a predetermined direction when subjected to heat is positioned in a location at which it is subjected to the heat of the electrical arc across the breaker contacts upon each interruption of the energizing circuit and at which the deflection thereof reduces the length of time the breaker contacts are closed.

United States Patent 91 Sloan, Jr.

[4 1 May 22, 1973 [75] Inventor: Clark E. Sloan, Jr., Anderson, Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Nov. 30, 1971 21 Appl. No.: 203,223

[52] US. Cl ..337/108, 340/388 [51] Int. Cl. ..I-I0lh 37/52 [58] Field of Search ..337/l6, 22, 27, 108;

[56] References Cited UNITED STATES PATENTS 1,947,037 2/1934 Daley ..337/108 3,271,760 9/1966 Sloan, Jr ..340/388 FOREIGN PATENTS OR APPLICATIONS 299,863 3/1916 Germany ..337/l08 Primary Examiner-Roy N. Envall, Jr.

Attorney-Eugene W. Christen, Creighton R. Meland and Richard G. Stahr 57 ABSTRACT A vibrator type electrical circuit interrupter having normally closed breaker contacts which establish an energizing circuit for an associated electrical coil and which are operated to an electrical circuit open condition upon the energization of the coil to interrupt the energizing circuit. A bimetallic element of the type which deflects in a predetermined direction when subjected to heat is positioned in a location at which it is subjected to the heat of the electrical arc across the breaker contacts upon each interruption of the energizing circuit and at which the deflection thereof reduces the length of time the breaker contacts are closed.

1 Claim, 8 Drawing Figures Patented May 22, 1973 2 Sheets-Sheet 1 ATTORNEY VIBRATOR TYPE ELECTRICAL CIRCUIT INTERRUPIER This invention is directed to a vibrator type electrical circuit interrupter and, more specifically, to a vibrator type electrical circuit interrupter including a bimetallic element of the type which deflects in a predetermined direction when subjected to heat which is positioned at a location at which it is subjected to the heat of the electrical arc across the breaker contacts upon each interruption of an associated energizing circuit and at which the deflection thereof reduces the length of time the breaker contacts are closed.

With many applications of vibrator type electrical circuit interrupters having normally closed breaker contacts which establish an energizing circuit for an associated electrical coil and which are operated to an electrical circuit open condition upon the energization of the coil to interrupt the energizing circuit, the electrical coil conductors are of an insufficient size to carry rated current for prolonged periods of operation.

However, it may not be desirable to completely interrupt the coil energizing circuit after a predetermined period of operation for a variety of reasons. Consequently, a protective device of the type which, with prolonged operation, operates in response to the heat generated by the arc across the breaker contacts upon each interruption of the coil energizing circuit to reduce the average current flow through the coil is desirable.

It is, therefore, an object of this invention to provide an improved vibrator type electrical circuit interrupter.

It is another object of this invention to provide an improved vibrator type electrical circuit interrupter having normally closed breaker contacts which establish an energizing circuit for an associated electrical coil and which are operated to an electrical circuit open condition upon the energization of the coil to interrupt the energizing circuit including a protective feature which operates in response to the heat generated by the electrical arc across the breaker contacts upon each interruption of the energizing circuit to reduce the average current flow through the coil.

In accordance with this invention, a vibrator type electrical circuit interrupter having normally closed breaker contacts which establish an energizing circuit for an associated electrical coil and which are operated to an electrical circuit opened condition upon the energization of the coil to interrupt the energizing circuit is provided wherein a bimetallic element of the type which deflects in a predetermined direction when subjected to heat is positioned in a location at which it is subjected to the heat of the electrical arc across the breaker contacts upon each interruption. of the energizing circuit and at which the deflection thereof reduces the length of time the breaker contacts are closed.

For a better understanding of the present invention, together with additional objects, advantages and features thereof, reference is made to the following description and accompanying drawings in which:

FIG. 1 is a plan view of an electromagnetic automotive type horn,

FIG. 2 is a sectional view of FIG. 1 taken along lines 2-2 and looking in the direction of the arrows,

FIG. 3 is a sectional view of FIG. 2 taken along lines 3-3 and looking in the direction of the arrows,

FIG. 4 is a section of the vibrator type electrical circuit interrupter of this invention taken along lines 44 of FIG. 3 and looking in the direction of the arrows,

FIG. 5 is an end view of FIG. 4,

FIG. 6 is a sectional view of an alternate embodiment of the vibrator type electrical circuit interrupter of this invention,

FIG. 7 is a sectional view of another alternate embodiment of the vibrator type electrical circuit interrupter of this invention, and

FIG. 8 is a sectional view of a third embodiment of the vibrator type electrical circuit interrupter of this invention.

Throughout the several figures of the drawing, like elements have been assigned like characters of reference.

One example, and without intention or reference of a limitation thereto, of a typical application of a vibrator type electrical circuit interrupter of this invention is with electromagnetically operated automotive type horns which are usually designed for intermittent duty. Horns of this type operate on a vibrator motor principle whereby a plunger operated by an operating electrical coil cycles a metal diaphragm which creates the moving air column. At one end of its travel, the plunger strikes a contact arm causing the contacts to open thus deenergizing the operating coil. During normal operation, peak instantaneous operating coil energizing current will exceed 15 amperes during horn startup which reduces to an average value of approximately 5 amperes as cycling continues. Even at the 5 ampere average energizing current, the operating coil may be destroyed with prolonged, continuous horn operation.

The vibrator type electrical circuit interrupter of this invention is of the type having normally closed breaker contacts which establish an energizing circuit for an associated electrical coil and which are operated to an electrical circuit open condition upon the energization of the coil to interrupt the energizing circuit and is most clearly seen in FIGS. 4, 6, 7 and 8. The vibrator type circuit interrupter consists of a stationary contact 10 and a movable contact 11 carried by a reciprocative member 12 which is a spring or which may be spring biased to move movable contact 11 in a direction toward stationary contact 10.

FIG. 1 is a plan view of a typical electromagnetically operated automotive type horn with which the vibrator type electrical circuit interrupter of this invention may be employed. The motor or operative member of a horn of this type consists of an electrical coil 14, best seen in FIG. 3. Terminal end 14a of coil 14 is wrapped around and is in electrical contact with rivet 15 to which is secured an input terminal member 16, FIG. 2, electrically insulated from the metal horn back shell assembly 17 by an insulating washer 18. Terminal end 14b of coil 14 is in electrical contact with reciprocative member 12, as is best seen in FIGS. 4, 6, 7 and 8, and is insulated from the horn back shell assembly 17 by an insulating member 20. Positioned within coil 14 is an associated movable core or armature member 21, as is shown in FIG. 2. Electrical coil 14, when energized, linearly drives movable core member 21 in a vertical direction downward as looking at FIG. 2.

One output terminal of a direct current supply potential source such as an automotive type storage battery, not shown, may be connected to input terminal 16 and the other output terminal may be connected to the horn back shell assembly 17 through a mounting bracket 32 and the automobile frame in a manner well known in the automotive art. With a source of direct current supply potential connected across input terminal 16 and the horn back shell assembly 17, an energizing circuit for coil 14 may be traced from input terminal 16, through rivet 15, FIG. 3, coil 14, reciprocative member 12, FIG. 4, rivet 26, movable contact 11 and stationary contact 10, rivet 27, support member 30, rivet 28, insulated from reciprocative member 12 by insulating member 20, and horn back shell assembly 17. Consequently, normally closed breaker contacts and 1 1 of the electrical circuit interrupter of this invention established an energizing circuit for the associate of electrical coil 14 and, when operated to an electrical circuit opened condition by the movement of armature 21 upon the energization of coil 14, interrupt the energizing circuit for coil 14 in a manner well known in the art.

To provide the feature which reduces the magnitude of the average energizing current of coil 14 with prolonged periods of operation, a bimetallic element of the type which deflects in a predetermined direction when subjected to heat is positioned in a location at which it is subjected to the heat of the electrical arc across the breaker contacts upon each interruption of the energizing circuit and at which the deflection thereof reduces the length of time the breaker contacts are closed.

Bimetallic element 25, FIG. 4, is mounted upon reciprocative member 12 through rivet 26, which also secures movable contact 11 to reciprocative member 12 and is positioned in such a manner that the edge 25a is operatively engaged by the shoulder 22 of armature 21, as best shown in FIG. 3. With bimetallic element 25 so positioned, upon the energization of coil 14 to drive armature 21 in a vertical direction downward, as looking at FIG. 2, shoulder 22 operatively engages edge 25a thereof and operates reciprocative member 12 in a direction to move movable contact 11 out of electrical contact with stationary contact 10. It has been found that one corner of edge 25a may be slightly bent, as shown in FIG. 5, to provide a more accurate contact with shoulder 22 of armature 21.

Located as shown in FIGS. 3 and 4, bimetallic element 25 is subjected to the heat of the electrical arc across breaker contacts 10 and 11 upon each interruption of the energizing circuit of coil 14. The low expansion side 2SLE of bimetallic element 25 is on the upper side, as looking at FIG. 4. Consequently, upon being heated by the electrical arc across breaker contacts 10 and 11, edge 25a of bimetallic element 25 deflects in an upward direction, as looking at FIG. 4. When deflected upward, edge 25a of bimetallic element 25 is contacted by shoulder 22 of armature 21 earlier during each stroke of armature 21 upon each energization of coil 14, a condition whichoperates contacts 10 and 11 to the electrical circuit open condition earlier during each stroke of armature 21. Consequently, breaker contacts 10 and 11 are operated to the electrical circuit open condition for a longer period upon the deflection of bimetallic element 25. This condition reduces the average energizing current flowing through coil 14, thus permitting a prolonged continuous operation of coil 14 without destruction.

From this description, it is apparent that bimetallic element 25, mounted upon reciprocative member 12, is in a location at which it is subjected to the heat of the electrical arc across breaker contacts 10 and 11 upon each interruption of the energizing circuit of coil 14, is positioned to be operatively engaged by shoulder 22 of movable core 21 and is so oriented that the breaker contacts 10 and 11 are operated to the electrical circuit open condition for a longer period upon the deflection thereof, thereby reducing the length of time breaker contacts 10 and 11 are closed.

With the embodiment just described, bimetallic element 25 conducts very little, if any, of the energizing current of coil 14. The heat required to produce a deflection thereof is provided solely by the heat of the electrical arc across breaker contacts 10 and 11 upon each interruption of the energizing circuit of coil 14.

In the embodiment of FIG. 6, stationary contact 10 is secured to bimetallic element 25 which is, in turn, secured, pre-loaded in a bent configuration, to support member 30. With this embodiment, reciprocative member 12 may have an enlarged end portion 12a which is positioned and arranged to be operatively engaged by shoulder 22 of armature 21 to operate breaker contacts 10 and 11 to the electrical circuit open condition upon each energization of coil 14. With this embodiment, the low expansion side 25LE of bimetallic element 25 is on the lower side, as looking at FIG. 6. Consequently, upon being heated by the heat of the electrical arc across breaker contacts 10 and 11, the unsupported center portion of bimetallic element 25 deflects in an upward direction, as looking at FIG. 6, into the raised section 30a of support member 30 to move stationary contact 10 in a direction away from movable contact 1 1. As movable contact 1 1 is mounted upon reciprocative member 12 which is a spring or is spring biased to move movable contact 11 in a direction toward stationary contact 10, movable contact 1 1 follows stationary contact 10 to place the enlarged end of armature 12a of reciprocative member 12 closer to shoulder 22 of armature 21. Consequently, armature 21 operates contacts 10 and 11 to the electrical circuit open condition earlier during each of its strokes upon each energization of coil 14 in a manner as described to the embodiment of FIG. 4. With stationary contact 10 mounted upon bimetallic element 25, bimetallic element 25 is subjected to the heat of the electrical arc across breaker contacts 10 and 11 upon each interruption of the energizing circuit of coil 14 and is so oriented that the breaker contact 10 mounted thereon is moved in a direction away from the other breaker contact, movable contact 11, upon the deflection of bimetallic element 25.

The embodiment of FIG. 7 is substantially identical to that of FIG. 6, with the exception that, instead of a raised portion 30a, a hole 34 is provided in support member 30 to permit bimetallic element 25 to deflect in an upward direction, as looking at FIG. 7, upon being heated by the electrical arc across breaker contacts 10 and 11. It may be noted that bimetallic element 25 is pre-loaded in a bent configuration to provide support at both ends but not in the center.

In the embodiment of FIG. 8, bimetallic element 25 is the support member to which stationary contact 10 is secured. As with the embodiments of FIGS. 6 and 7, the low expansion side 25LE of bimetallic element 25 is on the bottom side, as viewing FIG. 8. Consequently, upon being heated by the heat of the electrical arc across breaker contacts 10 and 11, bimetallic element 25 deflects in a vertical direction upward to move stationary contact in a direction away from movable contact 11, as do the other embodiments.

Although, in the embodiments in FIGS. 6, 7 and 8, bimetallic element 25 carries some of the coil 14 energizing current, it is of an insufficient magnitude to produce deflection thereof. Experimentation has shown that the heat produced by the electrical arc across breaker contacts 10 and 11 upon each interruption of the energizing circuit of coil 14 has reached approximately 550 P. which is of sufficient magnitude to heat bimetallic element 25 sufficiently to produce the required deflection.

Although with most applications it is only necessary that the average magnitude of operating coil energizing current be maintained less than a predetermined maximum, other applications may require that the operating coil energizing circuit be interrupted after a prolonged operation of a predetermined duration. Bimetallic element 25 may be so designed that sufficient deflection is produced by the heat of the arc to prevent the reclosing of the contacts. This will interrupt the operating coil energizing circuit completely to terminate operation until bimetallic element 25 cools sufficiently to permit contact closure. At this time operation will spontaneously restart.

While several embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that various modifications and substitutions may be made without departing from the spirit of the invention which is to be limited only within the scope of the appended claims.

I claim:

1. A vibrator type electrical circuit interrupter having a stationary breaker contact secured to a support member and a normally closed movable breaker contact carried by a reciprocative member which establish an energizing circuit for an associated electrical coil which linearly drives an associated movable core which operates said breaker contacts to an electrical circuit open condition upon the energization of the coil to interrupt the energizing circuit comprising,

a bimetallic element of the type which deflects in a predetermined direction when subjected to heat, and

means for mounting said bimetallic element upon said reciprocative member at a location at which it is subjected to the heat of the electrical arc across said breaker contacts upon each interruption of said energizing circuit in a position at which it will be operatively engaged by said movable core and so oriented that said breaker contacts are operated to the electrical circuit open condition for a longer period upon the deflection thereof. 

1. A vibrator type electrical circuit interrupter having a stationary breaker contact secured to a support member and a normally closed movable breaker contact carried by a reciprocative member which establish an energizing circuit for an associated electrical coil which linearly drives an associated movable core which operates said breaker contacts to an electrical circuit open condition upon the energization of the coil to interrupt the energizing circuit comprising, a bimetallic element of the type which deflects in a predetermined direction when subjected to heat, and means for mounting said bimetallic element upon said reciprocative member at a location at which it is subjected to the heat of the electrical arc across said breaker contacts upon each interruption of said energizing circuit in a position at which it will be operatively engaged by said movable core and so oriented that said breaker contacts are operated to the electrical circuit open condition for a longer period upon the deflection thereof. 